Method of securing a thread to a bobbin and a thread wound bobbin

ABSTRACT

The thread is heat sealed to the bobbin either by flowing the material of the bobbin about the thread or by sealing the thread directly to the bobbin under heat and pressure. Either one of the thread or bobbin must be made of a thermoplastic material.

United States Patent McLain METHOD OF SECURING A THREAD TO A BOBBIN AND A THREAD WOUND BOBBIN Inventor: Philippe Hardy-The Columbia, SC.

S00 Valley Company, Columbia, SC.

Filed: Oct. 6, 1970 Appl. No.: 78,496

McLain,

Assignee:

US. Cl. ..242/125.1, 242/118.7, 242/164, 242/172, 264/249 Int. Cl. ..B65h 75/28 Field of Search.....242/125.l, 125.2, 125, 125.3, 242/118.7,163,164,172,173,159,l18.2; 264/249 1 March 6, 1973 [56] References Cited UNITED STATES PATENTS 2,999,962 9/1961 Wahl ..242/125.1 X 2,460,807 2/1949 Chanowitz ..242/164 X 3,501,110 3/1970 Hopgood et a1 ..242/118.7

Primary ExaminerGeorge F. Mautz Attorney-Kenyon & Kenyon Reilly Carr & Chapin [57] ABSTRACT The thread is heat sealed to the bobbin either by flowing the material of the bobbin about the thread or by sealing the thread directly to the bobbin under heat and pressure. Either one of the thread or bobbin must be made of a thermoplastic material.

16 Claims, 10 Drawing Figures METHOD OF SECURING A THREAD TO A BOBBIN AND A THREAD WOUND BOBBIN This invention relates to a method of securing a thread to a bobbin and to a thread wound bobbin.

Heretofore, various techniques have been known for securing a thread to a bobbin or spool. For example, in some cases, an end of the thread has first been secured by a piece of tape or beeswax to a spool core and thereafter the thread has been wound up on the core. In

. other cases, a recess has been formed in the spool core and the free end of the thread has been frictionally engaged therein. Thereafter, the thread has been wound up on the spool core. In still other cases, various other types of mechanical attachments have been provided on the spools or bobbins in order to trap the end of a thread therein for purposes of winding up the thread on the spool or bobbin.

These various techniques, however, have not been entirely suitable. For example, in the case where a thread end has been frictionally engaged within a recess of a bobbin, there is a possibility that the thread can be slipped out of the recess before winding is commenced. In order to prevent this, the end of the thread has frequently been provided with a knot or bulge. However, this knot or bulge subsequently prevents the thread from going through the eye of a sewing machine needle and thus can be a cause of concern thereafter. In other cases where mechanical attachments are provided on the bobbin, such have added an additional expense to the manufacture of the bobbins. Also, in those cases where the thread ends have been secured manually to the bobbin, an additional expense is incurred due to the labor involved as well as the amount of time required in order to provide for a proper attachment of the thread to the bobbin.

Accordingly, it is an object of this invention to provide a means of easily and automatically securing the starting end of a thread to a bobbin.

It is another object of this invention to provide a threaded bobbin which upon unwinding allows the fastened end of the thread to be pulled free of the bobbin easily and quickly.

It is another object of this invention to provide a method of quickly and easily attaching a bobbin thread to a spool.

It is another object of this invention to provide a thread wound bobbin from which the thread can be unwound in a simple and easy manner.

It is another object of this invention to provide a thread wound bobbin of relatively low cost.

Briefly, the invention provides a method of securing a thread to a bobbin wherein at least one of the thread and bobbin is formed of a thermoplastic material as well as a thread wound bobbin of simple construction.

The method of the invention includes the steps of positioning a portion of the thread on a portion of the bobbin and of applying heat and pressure to the thermoplastic portion of the thread and bobbin portions to cause the heated thermoplastic portion to flow and become heat sealed to the other portion. In the case where the bobbin is made of thermoplastic material, the heat and pressure are applied so as to cause the portion of the bobbin contacting the thread to flow about the thread in order to entrap the thread within the bobbin. Upon cooling of the bobbin, the thread is securely held in place, however, this securement is such that the thread can be slipped from the bobbin upon the application of a sufficient force so that the entire thread can be removed from the bobbin, for example, during the operation of a sewing machine in which the bobbin is placed.

In order to apply heat and pressure, a single electrically heated temperature controlled rod or die can be used. Such a die can have a flat surface or a curved surface which matches the bobbin diameter so as to heat substantially all of the portion of the bobbin adjacent to the thread. Also, the rod or die can have a V-shaped groove so as to receive the thread therein while heating spaced portions of the bobbin so as to form the bobbin material in a manner to cover the thread more thoroughly.

In the case where the thread is of thermoplastic material, the thread itself is heated under pressure so as to become heat sealed directly to the bobbin.

It is noted that the invention can be utilized so long as at least one of the thread and bobbin are made of thermoplastic material. For example, the thread can be made of metal, plastic, or plastic coated wire, while the bobbin is made of a thermoplastic material having a lower melting point than the thread. Conversely, the bobbin can be made of metal, non-thermoplastic material, or thermoplastic material while the thread is made of a thermoplastic material having a lower melting point. As further example, a In Nylon monofilament or multifilament thread can be heat sealed to Nylon 6, polystyrene ABS or polypropylene bobbins. These bobbins could be used for plain or coated copper wire, cotton thread, polyester thread, acrylic thread, rayon thread, as well as other natural fiber threads. Furthermore, the thread can be of round cross-section or can be a ribbon. Also, the thread can be a monofilament or a multifilament.

The thread wound bobbin of the invention constitutes the combination of a bobbin and a thread wound on the bobbin, at least one of which is made of a thermoplastic material, and the thread has a portion near one end which is secured to the bobbin by heat sealing.

These and other objects and advantages of the invention will become more apparent from the following detailed description and accompanying drawings in which:

FIG. 1 illustrates a perspective view of a free end of a thread heat sealed to a bobbin according to the invention;

FIG. 2 illustrates a partial cross-sectional end view of a thread in position on a bobbin for application of heat and pressure to the bobbin according to the invention;

FIG. 3 illustrates a fragmentary view of a thread entrapped within a portion of a bobbin heated by a grooved heated rod;

FIG. 4 illustrates a cross-sectional view of a thread entrapped within a bobbin according to the invention;

FIG. 5 illustrates a ribbon secured to a bobbin by a grooved heated rod according to the invention;

FIG. 6 illustrates a view of a round thread in position on a bobbin prior to securement thereto according to the invention;

FIG. 7 illustrates a cross-sectional view of a heat sealed portion of a round thread which has been secured to a portion of a bobbin;

FIG. 8 illustrates a modified structure according to the invention having a pair of ends of a metal wire extending from a core of a spool according to the invention;

FIG. 9 illustrates a cross-sectional view of a plastic coated wire in position on a core of a spool prior to securement thereto according to the invention; and

FIG. 10 illustrates a cross-sectional view of the plastic coated wire of FIG. 9 heat sealed to the core of the spool.

Referring to FIG. 1, a bobbin I1 is formed with a core 12 of generally cylindrical cross-section and a pair of circular flanges 13 at the ends of the core 12. A thread 14, for example, of round cross-section has an end which is secured to a portion 15 of the bobbin core surface so that the remainder of the thread can be wound up on the core 12. Both the bobbin 11 and thread 14 are made of thermoplastic material; however, the spool 11 is made of a material which has a lower melting point than the material of the thread 13. For example, the thread 14 can be made of a thermoplastic Nylon monofilament which has a melting point of 418 F while the bobbin 1 1 is of another suitable therm'oplastic material.

Referring to FIGS. 2 and 3, in order to secure the thread 14 to the core 12 of the bobbin 11, an electrically heated temperature controlled rod 16 or other suitable means is positioned between the flanges 13 of the spool 11 with the thread 14 positioned under the rod 16. The lower surface 17 of the rod 15 is flat or curved transversely to conform to the contour of the core 12 and is provided with a V-shaped longitudinal groove 18 therein which is sized to straddle the thread 14. The rod 16 is heated and is pressed against the bobbin core surface (FIG. 3) so as to cause the portion 15 of the bobbin 11 influenced by the heat and pressure of the rod to soften and flow about the portion of the thread 14 within the V-shaped groove 18. After a sufficient length of time suitable for permitting a sufficient amount of bobbin material to flow about the thread 14 so as to trap the thread 14 therein, the rod 16 is removed and the bobbin 11 is permitted to cool so as to solidify the material surrounding the thread 14. The thread 14 is thus circumferentially entrapped and secured within the bobbin 11 (cf. FIG. 4).

The securement of the thread 14 in the bobbin 1] is such that the integrity of the thread 14 portions within and adjacent to the deformed bobbin portion 15 is substantially maintained i.e. the shape is maintained and the thread 14 is not made integral with the bobbin material. Thus, the thread 14 can be subsequently pulled from the bobbin 11 when a sufficient pulling force is exerted on the thread, e.g. when the thread 14 is pulled during an unwindingoperation when utilized in a sewing machine. However, the force required is such that the thread would not be inadvertently pulled from the bobbin during manufacture.

Referring to FIG. 5, wherein like reference characters refer to like parts above, instead of using a thread of round cross-section, a ribbon 19 of material can also be secured to the core 12 of a bobbin 11. In this case, the rod 16 for heating and pressing against the core 12 is formed with a substantially rectangular shaped groove 20 so as to have the ribbon 19 positioned therein.

It is noted that the use of the V-shaped groove 18 (FIG. 3) or the rectangular groove 20 (FIG. 5), where the ribbon is used, permits the plastic material of the bobbin 11 to cover over the thread 14 more thoroughly than if a smooth surfaced rod were used.

Referring to FIG. 6, wherein like reference characters indicate like parts as above, the relative melting points of the thread 14 and bobbin 1 1 can be reversed. That is, the thread 14 can be made of a material which has a lower melting point than the material of the bobbin 11. For example, the thread 14 can be made of a thermoplastic Nylon monofilament while the bobbin 1 1 is made of metal. In this case, a portion of the thread 14 resting on the core 12 is subjected to heat and pressure directly from a rod 21 having a smooth flat lower surface 22 and is deformed under heat and pressure into a flattened shape so as to be heat sealed to the core surface of the bobbin (cf. FIG. 7).

Referring to FIGS. 8 to 10, the invention can also be utilized in forming a transformer core or other similar structure. To this end, a spool 22 having a pair of flanges 23 of relatively large diameter and a core 24 of smaller diameter is provided with a coil 25 of metal wire 26 such as copper wire. The metal wire 26 is encased within a coating 27 of thermoplastic material which is of a lower melting point than the material of the spool 22 while the spool 22 is made of a thermoplastic material or any other suitable material.

Referring to FIG. 8, in order to secure the wire 26 to the spool 22, a portion 28 of the plastic coated wire 26 spaced from a free end of the wire 26 is heat sealed to either a flange 23 of the spool 22 or to the surface of the spool core 24 as above described by a suitable tool 21. This allows a short tag end 29 of the starting end of the wire 26 to project from the spool 22 so as to permit an electrical connection (not shown) to be made thereto. The wire 26 is then wound about the core 24 to form the coil 25 and is severed to form a second tag end to provide for a further electrical connection.

In accordance with the invention, the heat sealing of the thread and bobbin can also be carried out by the use of radio frequency methods, for example, as are used to spot weld various plastic materials, or ultrasonic energy methods wherein ultrasonic energy is converted to heat at a point of contact, as is known in fastening or sealing plastic parts together. In any of the methods used to subject the thermoplastic materials to sufficient heat to cause a flow of material, pressure may be applied to the thread or to the thread and bobbin to more efficiently obtain the heat sealing effect of the invention.

The invention thus provides a technique of securing a thread to a bobbin in a simple efficient reliable manner. Further, the invention provides a thread wound bobbin or spool which can be readily used in any suitable environment, for example, for use in a sewing machine or in an electrical device. Because of the simple securement of the thread to the bobbin, when being unwound from the bobbin, the thread can be easily pulled under a sufficient force from the deformed portion of the spool. It is to be noted that any slight deformation of the thread, if any, with respect to the bobbin or vice versa in the area of attachment is sufficiently slight so as not to interfere with the pulling of the thread from the bobbin under the intended force.

The free end of the thread can then be utilized, for example, for passing through the eye of a sewing machine needle, without obstructing other components of the system to which the thread is unwound.

The invention further provides a technique which can be utilized on a high speed basis in automatic machinery. Thus, the cost of labor and equipment can be substantially reduced over relatively short time periods. This, in turn, permits a thread wound bobbin to be produced at a relatively low cost. Furthermore, since the bobbins can be made of relatively inexpensive materials, the overall cost of the threaded bobbin is further reduced.

The invention further permits the use of a bobbin having unencumbered surfaces so that there is no need to produce or otherwise obtain bobbins with complex thread securing means thereon.

What is claimed is:

l. The combination of a synthetic plastic bobbin having a core and a synthetic plastic thread wound on said bobbin, said thread having at least one portion adjacent the inner end thereof heat sealed to said core, at least one of said bobbin and said thread being made of synthetic thermoplastic material to permit heat sealing of said portion of said thread with said bobbin.

2. The combination as set forth in claim 1 wherein said bobbin is made of synthetic thermoplastic material and said portion of said thread is secured in a flowed over portion of said bobbin.

3. The combination as set forth in claim 1 wherein said thread is made of synthetic thermoplastic material having a lower melting point than said bobbin.

4. The combination as set forth in claim 1 wherein said thread has a round cross-section.

5. The combination as set forth in claim 1 wherein said thread is of ribbon shape.

6. The combination as set forth in claim 1 wherein said thread is made of synthetic thermoplastic material and said portion of said thread is heat sealed to said bobbin.

7. The combination as set forth in claim 6 wherein said bobbin is made of a material having a higher melting point than said synthetic thermoplastic thread.

8. A method of securing a thread to a bobbin having a core wherein at least one of the thread and bobbin is formed of synthetic thermoplastic material, said method comprising the steps of positioning a portion of the thread on a portion of the core, and applying heat and pressure to the thermoplastic portion of said portions to cause said heated thermoplastic portion to become heat sealed to the other portion without said portions becoming integral with each other.

9. A method as set forth in claim 8 wherein the bobbin is made of a synthetic thermoplastic material to flow around the thread portion and secure the thread portion to the bobbin upon being subjected to the application of the heat and pressure.

10. A method as set forth in claim 8 which further comprises the step of utilizing a rod for applying said heat and pressure to the thermoplastic portion of said portions to cause said heated thermoplastic portion to become heat sealed to the other portion.

11. A method as set forth in claim 10 wherein said bobbin is made of thermoplastic material and said rod includes a groove therein for straddling of said thread,

wherein said step of applying heat and pressure includes the further step of circumferentially encasing said thread portion in said thermoplastic portion of said bobbin.

12. A method as set forth in claim 8 wherein said thread is made up of a synthetic thermoplastic material having a lower melting point than the material of the bobbin.

13. A method as set forth in claim 8 which further includes the step of extending a free end of the thread from said spool adjacent to said portion secured to the spool, winding the thread about the core portion of the spool and extending a second end of the thread from said spool.

14. A method of securing a thread to a bobbin having a core wherein at least one of the thread and bobbin is formed of synthetic thermoplastic material, said method comprising the steps of positioning a portion of the thread on a portion of the core, and applying heat to the thermoplastic portion of said portions to cause said heated thermoplastic portion to become heat sealed to the other portion without said portions becoming integral with each other.

15. A method as set forth in claim 14 wherein the bobbin is made of a synthetic thermoplastic material to flow around the thread portion and secure the thread portion to the bobbin upon being subjected to the application of the heat.

16. The combination of a bobbin having a pair of flanges and a core extending between said flanges and a coil of synthetic plastic coated metal wire wound about said core and having a first tag end extending from said bobbin and a second tag end extending from said bobbin, said coil having at least one portion thereof heat sealed to either said flange or core of said bobbin, said bobbin being made of synthetic thermoplastic material to permit heat sealing of said portion of said coil with said bobbin. 

1. The combination of a synthetic plastic bobbin having a core and a synthetic plastic thread wound on said bobbin, said thread having at least one portion adjacent the inner end thereof heat sealed to said core, at least one of said bobbin and said thread being made of synthetic thermoplastic material to permit heat sealing of said portion of said thread with said bobbin.
 1. The combination of a synthetic plastic bobbin having a core and a synthetic plastic thread wound on said bobbin, said thread having at least one portion adjacent the inner end thereof heat sealed to said core, at least one of said bobbin and said thread being made of synthetic thermoplastic material to permit heat sealing of said portion of said thread with said bobbin.
 2. The combination as set forth in claim 1 wherein said bobbin is made of synthetic thermoplastic material and said portion of said thread is secured in a flowed over portion of said bobbin.
 3. The combination as set forth in claim 1 wherein said thread is made of synthetic thermoplastic material having a lower melting point than said bobbin.
 4. The combination as set forth in claim 1 wherein said thread has a round cross-section.
 5. The combination as set forth in claim 1 wherein said thread is of ribbon shape.
 6. The combination as set forth in claim 1 wherein said thread is made of synthetic thermoplastic material and said portion of said threAd is heat sealed to said bobbin.
 7. The combination as set forth in claim 6 wherein said bobbin is made of a material having a higher melting point than said synthetic thermoplastic thread.
 8. A method of securing a thread to a bobbin having a core wherein at least one of the thread and bobbin is formed of synthetic thermoplastic material, said method comprising the steps of positioning a portion of the thread on a portion of the core, and applying heat and pressure to the thermoplastic portion of said portions to cause said heated thermoplastic portion to become heat sealed to the other portion without said portions becoming integral with each other.
 9. A method as set forth in claim 8 wherein the bobbin is made of a synthetic thermoplastic material to flow around the thread portion and secure the thread portion to the bobbin upon being subjected to the application of the heat and pressure.
 10. A method as set forth in claim 8 which further comprises the step of utilizing a rod for applying said heat and pressure to the thermoplastic portion of said portions to cause said heated thermoplastic portion to become heat sealed to the other portion.
 11. A method as set forth in claim 10 wherein said bobbin is made of thermoplastic material and said rod includes a groove therein for straddling of said thread, wherein said step of applying heat and pressure includes the further step of circumferentially encasing said thread portion in said thermoplastic portion of said bobbin.
 12. A method as set forth in claim 8 wherein said thread is made up of a synthetic thermoplastic material having a lower melting point than the material of the bobbin.
 13. A method as set forth in claim 8 which further includes the step of extending a free end of the thread from said spool adjacent to said portion secured to the spool, winding the thread about the core portion of the spool and extending a second end of the thread from said spool.
 14. A method of securing a thread to a bobbin having a core wherein at least one of the thread and bobbin is formed of synthetic thermoplastic material, said method comprising the steps of positioning a portion of the thread on a portion of the core, and applying heat to the thermoplastic portion of said portions to cause said heated thermoplastic portion to become heat sealed to the other portion without said portions becoming integral with each other.
 15. A method as set forth in claim 14 wherein the bobbin is made of a synthetic thermoplastic material to flow around the thread portion and secure the thread portion to the bobbin upon being subjected to the application of the heat. 